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Stray rocket

The mystery object that passed just 500 000 kilo-metres from Earth on
5 December may be a stray booster rocket launched into deep space in the
1970s.

The European Southern Observatory has reported that the brightness of
the object fluctuated about once a minute. That would be expected from a
shiny booster rocket, but not from a rocky asteroid.

Brian Marsden of the Har vard Smithsonian Astrophysical Observatory
calculates the object’s last close approach to Earth was at 10 million kilometres
in December 1974. The date matches the launch of the German Helios satellite
into orbit around the Sun.

To settle the issue, Steve Ostro of the Jet Propulsion Laboratory plans
radar observations with the Goldstone Antenna in California and the Arecibo
Antenna in Puerto Rico in the next two weeks. A strong reflection would
indicate that the object is smooth and artificial.

If so, it would highlight another aspect of the space junk problem –
no one tracks debris outside Earth orbit.